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cheap leak test

Technical help for Series one, two and three Lambrettas. Models include the Li, Li Special, TV, SX, GP, Serveta and API/SIL models

Re: cheap leak test

Postby Sticky » Mon Oct 01, 2018 12:31 pm

NorthernJordan wrote:
So 5 mins with little/almost no pressure loss would be satisfactory?


Yes that's fine by the advice I've been given Jordan
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Re: cheap leak test

Postby ROClarke » Mon Oct 01, 2018 5:52 pm

Sticky wrote:
NorthernJordan wrote:
So 5 mins with little/almost no pressure loss would be satisfactory?


Yes that's fine by the advice I've been given Jordan

Surely depends on what pressure you start with.
Nothing will hold for 5 mins at over 10 psi I would suggest.
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Re: cheap leak test

Postby NorthernJordan » Mon Oct 01, 2018 7:23 pm

I was going by the regularly quoted 5 psi
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Re: cheap leak test

Postby kennystag » Wed Oct 03, 2018 8:24 am

Hi Grandpa,
What size of inner tube do you use for a 22mm carb and exhaust stubs.
Cheers
Stag
8-)
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Re: cheap leak test

Postby Warkton Tornado No.1 » Wed Oct 03, 2018 12:05 pm

Hi Kenny.

I've always had cycles knocking about, & I use an inner tube that was intended for a mountain bike, though a kiddie's cycle tyre size will do. "Waste not want not" so an inner tube well-used or punctured is what I grabbed & have been using every since.

A 1.75 is common enough, though 2.25 would not be so much a stretch & you can always clamp with worm drive clips if needs be.

I use the valve (as intended for the tube) to inflate because you can soon tell if there is a leak & since I've been doing the test, the only leaks have been @ the spark plug area, which can be difficult to seal if you want to retain the captive washer. One cylinder head with a spark plug thread insert was also a challenge.

Good Luck!

Mark
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Re: cheap leak test

Postby kennystag » Thu Oct 04, 2018 10:54 am

Thanks Mark,
Stag
8-)
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Re: cheap leak test

Postby Pompeydave » Mon Nov 12, 2018 7:16 pm

Hi all, I've just used the blood pressure valve and inner tube method for the first time- showed up a leak at the exhaust flange straightaway which is now gone after adding some sealant to the copper gasket. Does anyone know for sure what psi we should be testing at? No-one so far seems to know if the previously quoted 5psi is just a ball park figure, or is it based on knowledge from elsewhere?

***edit*** Just googled this and 5-6 psi held steady for five minutes is what almost everyone out there in cyberspace is recommending. Any more than 6 psi risks blowing the oil seals.
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Re: cheap leak test

Postby Martin s » Tue Nov 13, 2018 11:38 pm

This test showed leaking inlet manifold nuts, the obvious exhaust gasket, but most importantly for me, a leaky weld on a brand new exhaust u bend.
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